MINNEAPOLIS — Weeks before Christian Ponder’s shoulders slumped and his confidence was questioned, the Vikings went to Detroit and amassed an anemic 100 net yards passing.

Don’t remember griping about that one, eh?

Well, that’s because the Vikings won, 20-13. A 227-yard offensive output was swept aside because Percy Harvin returned the opening kickoff a franchise-record 105 yards for a touchdown and Marcus Sherels added a 77-yard punt return for a touchdown in the third quarter.

Six weeks later, things have changed. Harvin is unlikely to play because of a badly sprained left ankle, and the Lions’ special teams coverage units have gone from historically awful to among the league’s best the past five weeks.

“They’re not even the same special teams,” Vikings coach Leslie Frazier said. “They’re playing so, so much better as a group across the board.”

As Vikings special teams coordinator Mike Priefer notes, this group isn’t the same as the one the Lions had in September, when they became the first NFL team since at least 1940 to give up kickoff and punt returns for touchdowns in consecutive games.

“The thing about the NFL is if some guys can’t get it done, they bring in new guys,” Priefer said. “But for the most part, they’re doing the same things (schematically). They’re just doing them better. I think any time you get burned or a little bit embarrassed, you’re going to come back and play a little bit harder. You’re going to come out swinging.”

Since that loss to the Vikings, Lions special teams coach Danny Crossman has changed four players on his kickoff team and three on his punt team. Starters were asked to chip in. Rookie seventh-round pick Travis Lewis was moved from regular game-day inactive to replacing veteran Doug Hogue, who was released. Returner Stefan Logan is now on the kickoff team as well, young special teamer Ricardo Silva was added to the roster and Kassim Osgood has improved like a 10-year veteran should since missing a key tackle in that Vikings game.

“They seem to have a lot of new faces,” said Sherels, the favorite to return kickoffs if Harvin can’t play. “They’ve been playing fast and confident.”

The numbers agree.When the Lions limped into their Week 5 bye, they were last in the league in punt return coverage (27.3 yards per return) and 30th in kickoff return coverage (32.8). In the four games since their bye, the Lions are allowing 6.0 yards on 10 punt returns, with a long of 18; and 20.4 yards on 13 kickoff returns, with a long of 31.

“I would hope (we’ve improved) because we were at a low point,” Lions coach Jim Schwartz said. “I think we’ve seen improvement from some young players, we’ve put some other guys in a few different positions and we stuck with our scheme.”

Crossman deserves credit for not panicking. He went into that bye as the league’s most likely assistant to be fired. Yet he never flinched.

“We’re going to get it done,” he told reporters at the time. “End of story.”

A week later, the Lions went to Philadelphia and won 26-23 in overtime. The Eagles averaged 4 yards on three punt returns and 24.4 yards on five kickoff returns.

Even dangerous Philly returner DeSean Jackson lost 3 yards on his only punt return. A week later, Chicago’s even more dangerous returner, Devin Hester, had one punt return for 5 yards.

In the Lions’ past four games - which also include victories over Seattle and Jacksonville and a loss to the Bears - they’ve allowed only two kickoff returns beyond the 30-yard line. Both of them came at Philadelphia four weeks ago, and both of them were stopped at the 35.

Heading into their bye, the Lions ranked last in opponents’ starting position following a kickoff (28-yard line). In the Lions’ past four games, their opponents’ average starting position following a kickoff is the 21-yard line.

“I’ve been embarrassed before and maybe I worked longer that following week,” Priefer said. “You just demand a certain level of effort and expect them to play at a higher level when you do get burned.”